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E. W. SMITH &,J. H. MARS. STEAM BOILER.

IND. 30,258. Patented OottZ, 1860.

'HHHIHIIHIIII UNITED STATES PANT FTQE.

E. W. SMITH AND J. H. MARS, OF NEW YORK, N. Y.

STEAM-BOIL ER.

Specification of Letters Patent No. 30,258, dated October 2, 1860.

To all whom it may concern:

Be it known that we, ERASTUS W. SMITH, of New York city, residentengineer to the New York and Havre United States Mail Steam Ship Companyand JOHN H. MARS, of New York city, chief engineer of the steamshipAmgo, belonging to said company, have invented a certain new andImproved Steam-Boiler; and we do hereby declare that the following is afull and exact description thereof, reference being had to theaccompanying drawing, which represents a longitudinal section throughall the parts of our boiler.

The nature of our invention consists in a certain combination andarrangement'of a mixing or combustion chamber with two tiers of furnacesand a direct and returning series of fiues or of fiues and tubes wherebythe current of gases from the upper furnace is drawn down and mixed inthe middle and lower portion of the chamber and the mixture andcombustion is allowed to proceed in large flues at the base of theboiler and the heat is extracted in a series of smaller lines or tubeswhich series makes a partial return of the draft and discharges into anuptake immediately behind the upper furnace.

Two tiers of furnaces have often been employed with difierentarrangements of the fiues and chambers, and single return ascendingflues have been employed in boilers with single tiers of furnaces andhave in such boilers been arranged with the uptake directly behind thefurnaces but these features have not so far as we can learn beenemployed in connection or combination, each with the other. In ourinvention they are thus combined and are furthermore so arrangedrelatively to each other and to a combustion chamber which connects themthat our boiler possesses advantages not before attained in anyequivalent manner.

In managing boilers with two tiers of furnaces it is common to supplyfresh fuel to the two series alternately so that while the average ofthe gases discharged is in about its proper proportion one series offurnaces is liable to discharge volatile matter in an uncombined orunburned condition while the other is discharging an excess of freeoxygen or unchanged atmospheric air and it is desirable intimately tomix the gases discharged from the one series with the gases dischargedfrom the other series while their temperature is very high.

Our invention induces a degree of admixture of the gases from the twoseries before entering the fines and a continuation of the admixture andcombustion within the flues which has not before been attained in anyboiler with a double tier of furnaces.

In our invention the gases from the upper tier of furnaces are bentdownward in a suitable combustion chamber and mingle with the current ofgases ejected over the bridge from the lower tier of furnaces and thecombustion chamber or space in which they may thus mingle is extendeddownward to the base of the lower fiues, which latter are of largediameter and receiving the agitated gases allow combustion to proceedwhile they are traversing a considerable distance therein.

The gases from two tiers of furnaces have before been allowed to meetprevious to entering the fines but an equivalent extension of thecombustion chamber is for obvious reasons not practicable when the gasesare presented to each other at the bridge of the upper tier of furnaces,neither is it practicable to allow the gases to enter and burn in largeflues at such a level because fiues at such level are liable to beuncovered by the water and must be small and exposed to less heat inorder to sustain themselves under such conditions. They are furthermoreimmersed in water which at best is highly charged with particles ofsteam and is therefore less efficient in absorbing the heat from themetal. Our invention also allows the furnaces to occupy the whole depthof the boiler from the base to near the surface of the water and provides in connection with this a larger area for the draft than anyarrangement previously known in boilers with two tiers of furnaces. Thislarge area for the draft in each series allows of the employment of verysmall flues or tubes in the returning series and thus admits ofultimately extracting the heat very perfectly from the gases withoutsensibly retarding the draft. The use of tubes in lieu of liues in anyof the returning series is not practicable in any boilers with two tiersof furnaces before known because the space afiorded for such returnseries in former boilers of this type was too small to admit of suchminute subdivision of the current.

The small area in all former boilers was due to the necessity either fora double return as in the drop fiue style and consequently for dividingthe flue areas into three divisions or the necessity in single returnboilers of this character for traversing the space between the upperfurnaces and the surface of the water, thereby necessarily curtailingboth the height of the furnaces and the area of the returning series.

Two of our improved boilers in the proportions represented in thedrawing on a scale of three eighths of an inch equal one foot are in useon the U. S. mail steamship Fulton. As thus proportioned they have agood draft, are easily accessible at every part for repairs, arebelieved to have an active circulation in the water, promise to be verydurable and their'efiiciency and economy as compared with the two tieredfurnace boilers in the sister ship the Arago which are consideredexcellent, substantiate all that we have claimed for them.

To enable other skilled in the art to make and use our invention we willproceed to describe its construction by the aid of the drawing.

A is the shell of a boiler in any ordinary form. The water surfacetherein is denoted by a a.

B is the lower tier of furnaces.

C is the upper tier.

D is a connection or combustion chamber connecting C and D and extendingbelow the back end of B in the manner represented.

E is a series of flues the lower of which are of so large size as tocarry the principal portion of the draft and allow the freshly mixedgases to burn therein forming in some degree a continuation of thecombustion chamber. These fiues being below the points at which thegases pass over the bridge walls of either furnace compel a crosscurrent and an intimate admixture of the two currents in the middle andlower portion of the combustion chamber.

F is a back connection.

G is a series of tubes or small fines and H is a chamber located asrepresented into which the gaseous products of combustion .after theirentrance therein and to maintain a sufliciently high temperature toignite at every point at which a suitable measure of air meets asuitable measure of combustible gas, until nearly the whole extent ofthe flue is traversed. This is equal in effect or nearly equal to anextension of the combustion chamber along the bottom of the boiler. Thehigh temperature of the metal thereof is rapidly absorbed by the densewater with which these fiues are from their position certain to bealways covered.

e do not claim the employment of two series of furnaces, nor theemployment of a combustion chamber and fines arranged as describedexcept when the same are used in connection with two series of furnacesand arranged relatively thereto substantially as herein represented, but

Having now fully described our boiler what we claim as new therein anddesire to secure by Letters Patent is- The arrangement of the combustionchamber D relatively to the two tiers of furnaces and to the fines ortheir equivalents whereby the gases from the upper tier of furnaces aredrawn downward and mingled with those from the lower tier in the middleand lower portion of the combustion chamber and the agitation andcombustion is allowed to proceed in the large fiues along the bottom ofthe boiler and the heat is extracted in a series of smaller fiues ortubes which makes a partial return of the draft and terminates in anuptake or equivalent connection H immediately behind the upper furnacessubstantially as herein set forth.

In testimony whereof we have hereunto set our names in the presence oftwo subscribing witnesses.

ERASTUS W. SMITH. JOHN H. MARS. Witnesses:

THOMAS D. STETSON, A. SNYDER.

